Control system for hydrodynamic retarder

ABSTRACT

A control system is provided for use with a hydrodynamic retarder for providing braking to a vehicle by using engine lubricant as the working fluid. The system comprises a first pressure responsive, priority valve which functions to direct engine lubricant to a second, control valve from the engine lubricant pump only after the pressure in the engine lubricant system has achieved a sufficiently high level to supply the engine&#39;&#39;s requirements. In another embodiment, the first valve meters lubricant to both the engine and retarder at the same time by means of metering slots. The second control valve is operatoractuated and functions to direct lubricant through the heat exchanger, the lubricant filter, and then to the engine in one mode, or additionally by way of a hydrodynamic retarder in a second mode and thus to provide braking for the vehicle.

I w United States [15] 3,6 3 Clark et a1. Feb. d, 1972 [54] CONTROLSYSTEM FOR 3,526,304 9/1970 Pearce et al. ..l88/90 X HYDRODYNAMICRETARDER Primary ExaminerBenjamin W. Wyche [72] Inventors! :l Q l fi k mfi Attorney-Fryer, T jensvold, Feix, Phillips&Lempio orns, eorla; ra eur East Peoria, all of I11. 57 ABSTRACT Assigneei Caterpillar TractorPeoria, A control system is provided for use with a hydrodynamic re- 201970 tarder for providing braking to a vehicle by using engine lubri-[22] Flled Jan cant as the working fluid. The system comprises a firstpres- [21] Appl. No.: 4,338 sure responsive, priority valve whichfunctions to direct engine lubricant to a second, control valve from theengine lubricant pump only after the pressure in the engine lubricant[52] [1.8. CI. 1198217684, 112970217145, system has achieved a sumciemlyg level to pp y the em [51] I t. Cl 360k 29/02 6d 57/00 ginesrequirements. In another embodiment, the first valve 58] fi "192/3 4{88/90 90 A meters lubricant to both the engine and retarder at the sametime by means of metering slots. The second control valve isoperator-actuated and functions to direct lubricant through [56]References clued the heat exchanger, the lubricant filter, and then tothe engine D STATES PATENTS in one mode, or additionally by way of ahydrodynamic re- I ZZ S 192/4 B tarder in a second mode and thus toprovide braking for the 2,946,416 7 l9 noy which 3,283,859 11/1966Bertram.... ..l88/90 3,386,540 6/1968 l-lorsch ..192/4 B X 11 Claims, 2Drawing Figures i d'a ah PATENIEB FEB 81972 SHEET 2 {IF 2 INVENTORSRICHARD B. CLARK HUGH C. MORRIS GERALD E. WHIEHURST CONTROL SYSTEM FORHYDRODYNAMIIC RETARDER Hydrodynamic retarders are used on many largevehicles to supplement the vehicle service brakes when such servicebrakes are insufficient in and of themselves for braking the vehicle.Large earth-moving vehicles, for example, oftentimes require suchsupplemental braking to decrease the vehicles speed during operation.

Conventional retarders are arranged downstream of the engine andoftentimes downstream of the vehicles transmission and are actuatedselectively by suitable control means for supplemental braking purposes.These conventional retarder systems which are arranged to be used inconjunction with the transmission require control systems which have anextra pump for pumping transmission fluid to the retarder and a separateoil cooler for cooling the working fluid emanating from the retarder.This often results in a complex control system having to be tailored"for each type of vehicle application.

An engine-mounted retarder of the type described in copendingapplication U.S. Ser. No. 736,437, now Pat. No. 3,490,567, overcomesthis disadvantage since it forms part of the engines output and,therefore, may be used with a variety of transmissions without specialadaptations for each type of transmission. In the copending applicationa retarder is provided having the rotor thereof attached directly to theengine s crankshaft or power output shaft. The rotor is preferablypositioned between the crankshafts reannost support bearing and theengine s flywheel to provide a retarder assembly exhibiting a highdegree of structural integrity and which is less prone than conventionalretarders to cause damage to the engine and attendant components. Thesubject retarder is adapted to utilize the engine oil pump to supplybraking fluid to the retarder. The problem which has arisen whenutilizing the re tarder so described is that when engine oil is used asthe working fluid, the engine, when first started up, receives aninadequate supply of lubricant due to the fact that the retarder isbeing charged. This inadequacy of lubricant to the engine can, ofcourse, result in serious damage to the moving parts thereof.

It is therefore an object of this invention to provide a retardercontrol system which utilizes lubricating oil utilized in the engine'slubrication system as the working fluid for the retarder.

It is a further object of this invention to provide a retarder controlsystem which automatically directs engine oil to the engine duringstart-up and then, when sufiicient oil pressure is achieved, directs oilto the retarder through an operator-controlled valve.

it is a still further object of this invention to provide a retardercontrol system which directs engine oil to the retarder andsimultaneously meters sufficient oil to the engine to supply its needs.

it is a still further object of the retarder control system of thisinvention to insure that oil heated by the retarder is cooled beforereturning it to the engine.

It is a still further object of the retarder control system of thisinvention to provide a simple, compact control system unit which may bemounted directly on a vehicle engine and, using various parts of thenormal engine configuration, be used with various transmissions, thusalleviating the necessity of tailoring the system to a particular typeof engine used on a variety of vehicles.

These and other objects of this invention will become more readilyapparent from the following description and accompanying drawingswherein:

FIG. 1 shows a schematic-sectional illustration, partly in crosssection, of the retarder control system of this invention in associationwith a conventional engine having a crankshaft mounted retarder.

FIG. 2 shows a cross-sectional illustration of an alternative embodimentof the priority valve of the retarder control system of this invention.

Referring to FIG. 1, there is shown an engine-driven oil pump it),pressure relief valve 12, oil filter M, and heat exchanger 16, which areall part of the normal configuration of engine 18. Pump 10 is mounted onand driven by the engine. Mounted at the rear of engine 18 is ahydrodynamic retarder 20 having an inlet 22 and an outlet 24 with fluidflow direction indicated by arrows. The retarder control systemcomprises a first pressure responsive, priority valve generally shown at26 and a second, control valve shown generally at 28. Lubricant ispumped from the engine by means of pump 10 through a conduit 30 which isin communication with valve 26. Valve 26 contains a spool 32 which isbiased by a spring 34 to the position shown. A drain conduit 35 isprovided at the spring end of the valve.

During engine starting periods, when oil pressure is low, lubricant isdirected from the pump by way of conduit 30 around groove 36 in valvespool 32 and, by means of conduit 38, is directed to oil filter 14 andthence into the engine to accomplish its lubrication function. As engineoil pressure rises to normal, spool 32 compresses spring 34 due to theforce acting on the right end of the spool which results from pressurecommunicated by conduit 40 which is, in turn, in communication withconduit 38. in this manner, spool 32 moves to the left and groove 36brings conduits 30 and 42 into fluid communication. Conduits 38 and 42defining a first and second outlet means, respectively, are so spaced inrelation to the dimension of groove 36 that at some interim periodduring the movement of the spool, both conduits are in fluidcommunication with conduit 30 which defines an inlet means. Thus, asengine oil pressure rises gradually from zero at the start, lubricant isfirst channeled directly to the engine. At some interim period lubricantis directed both to the engine and to the retarder. At some later periodthe lubricant pressure achieves a sufficiently high value such that thedirect channel to the engine is cut oft", and all lubricant from thepump is channeled through conduit 42.

Oil thus flows around groove 36 from conduit 30 to conduit 42, thelatter conduit being connected to the retarder control valve 28. Oilthen flows through valve 28 by means of spool 44 with an annular groove46 communicating with a conduit 48 and thence heat exchanger 16. Oilthus flows through the heat exchanger where it is cooled sufiiciently tobe utilized in the engine. Oil or lubricant flows from the heatexchanger and a conduit 50 to an annular groove 52 and an annular groove54 which communicates with conduit 56 having a check valve 58 therein,and thence through oil filter 14 to engine 18. During starting of theengine, check valve 58 precludes flow of oil to control valve 28 inorder to prevent heat exchange 16 from filling and thus depriving theengine of a sufficient amount of lubricant for proper operation.

Control valve 28 is arranged to be actuated by a handle 68 of aircontrol valve 70 which meters air from an air pressure source (notshown) to conduit 71. Control valve 28 comprises a valve spool 44slidably arranged in a housing 72. Air control valve 70 is arranged tocontrol the air pressure in a chamber 74 at the left end of controlvalve 28. Valve spool 44 comprises lands 60 through 66 for selectivelypassing working fluid thereby, depending upon the position of the spool.A slug 7 6 is slidably arranged in the spool and abuts valve housing 72under the biasing action of two compression springs 78 and 80. The twosprings are arranged on both sides of a stop member 82 in such a mannerthat a dual spring rate is produced. Holes 84 and 86 are arranged in thespool to communicated fluid to the spring chamber from retarder inlet 22and outlet 24, respectively. The spring loaded poppet valve 88 isarranged to cooperate with a restricted passage 90 for purposeshereinafter explained. If needed, a more complete explanation of theoperation of valve 28, per se, may be had by referring to US. Pat. No.3,386,540, assigned to the same assignee as this invention.

When retarding is required, control valve 28 is arranged to be actuatedby air control valve 70 which controls the pressure in chamber 74. Uponactuation, spool 44' is moved to the right. Lands 60-66 are thusarranged to communicate fluid in line 42 with a conduit 92 for chargingretarder 20 through inlet 22. A retarder discharge conduit 94 isconnected to valve 28 and arranged to communicate with conduit 48 bylands 60 and 62. Fluid thus flows in conduit 48 to heat exchanger 16where it is cooled and returned to valve 28 by means of conduit 50 andmetered across land 66 and groove 54. The fluid is then directed throughline 56 to the engine by way offilter 14.

To deactivate the retarder, air pressure is removed from spool 44 byactuation of handle 68 of air control valve 70. Springs 78 and 80 movespool 44 to the leftmost position as shown in FIG. 1. Spool 44 thusdirects fluid to flow in the previously described manner. Becauseretarder 20 acts as a pump, oil remaining in it, after the retarder hasbeen removed from the circuit, is pumped through conduit 94, acrosslands 60 to an annular groove 96 and thence to a return conduit 98 thatleads to the engine pump 100. To insure adequate lubrication of theretarder seals, a poppet valve 88, communicating between groove 46 andgroove 102, permits a relatively small amount of oil to be delivered tothe retarder for cooling and lubrication when the retarder is not beingused.

Referring now to FIG. 2, there is shown an alternative embodiment of thepriority valve 26 which valve is designated generally 26. Priority valve26 may be bodily substituted for valve 26 in the previously describedretarder control system as shown in FIG. 1. Priority valve 26 functionsin a manner somewhat different than priority valve 26, as will behereinafter described.

Valve 28 consists ofa body 29 having an inlet 30 and out lets 38 and 42;a generally cylindrical spool 32 having an annular groove 33 and fourlongitudinal metering slots 37; a bore 39; a spring 34 contained betweenplate 41, having drain 35 therein, and spool 32, the spring urging thespool rightwardly against plate 43; and O-ring seals 45 and 47 sealingplates 41 and 43, respectively. Fastening means (not shown) serve toretain the plates on the body.

When bodily substituting alternative priority valve 26 for valve 26 inthe retarder control circuit shown in FIG. 1, fluid connection would beaccomplished between inlet 30' and conduit 30, drain 35 and conduit 35,inlet 38 and conduit 38, and inlet 42 and conduit 42. Conduit 40 shownin FIG. 1 is not needed with priority valve 26 and would therefore beeliminated.

During engine starting periods when oil pressure is low, lubricant isdirected from pump through conduit 30 to inlet 30' of valve 26'. Oilthen flows across groove 33 and through metering slots 37 in spool 32and, from outlet 38' by means of conduit 38, is directed to oil filter14 and thence into the engine to accomplish its lubrication function. Asthe oil pressure in outlet 38 rises to normal, pressure acting onfrustoconical face 370 causes spool 32' to be moved leftwardly againstthe force of spring 34 until outlet 42 is brought into fluidcommunication with inlet 30. Oil thus flows through the fluid circuitdefined by conduit 42, control valve 28, conduit 48, heat exchanger 16,and conduit 50. When this circuit is charged, oil exits through conduit56 to the oil filter 14 and thence to the engine. When fluid pressure inthe retarder circuit reaches a normal, as established by relief valve12, pressure is communicated to spool 32 through outlet 38 which causesthe spool to move fully to the left so all oil flow takes place by wayof the aforementioned fluid circuit prior to entering the engine.

When control valve 28 is actuated by means of handle 68 the large volumeof retarder begins to fill with lubricant. This causes a pressure dropin the circuit which is communicated to outlet 38'. The low-presurecondition acting on face 37a allows spool 32 to be moved rightwardly bythe action of spring 34 which reduces the flow through outlet 42'slightly and at the same time allows a minimum flow through meteringslots 37 and outlet 38 to the engine. The lubricant flow from pump 10 isthus divided with a minimum flow being channeled directly to the enginesufficient for its lubrication needs while the balance of the flow ischanneled to the retarder for vehicle braking. When retarder 20 isfilled or no longer needed and control valve 28 deactivates it, thepressure in the circuit rises to normal and spool 32 moves to the leftcompressing spring 34' under the force of the pressure at outlet 38'.All flow through outlet 38 is thus shut off and all flow is directedthrough outlet 42'.

It may be noted that oil and lubricant are used interchangeably in thisdisclosure. While oil, in the sense of a petroleum product, is normallyused in internal combustion engines utilizing the device of thisinvention, any sort of fluid lubricant may be used. Thus, it is not theintention to provide an invention utilizable only with oil but ratherwith a broad class of fluid lubricants.

In addition, while the above-described invention is particularly adaptedfor use with an engine-mounted retarder, it is not restricted to suchuse and, in fact, may be advantageously used with retarders which arenot engine mounted, e.g., transmission-mounted retarders.

It is understood that the foregoing description is merely illustrativeof preferred embodiments of the invention and that the scope of theinvention is not to be limited thereto, but is to be determined by thescope ofthe appended claims.

What is claimed is:

1. In an internal combustion engine having a pressurized lubricatingsystem, a control system comprising a pressurized lubricating fluidsource and a hydrodynamic retarder operatively associated with saidengine for selective braking purposes, retarder control valve meansoperatively connected to said fluid source and said retarder forselectively activating said retarder with said lubricating fluid, andpriority valve means operatively connected between said fluid source andsaid retarder control valve means and further operatively connected tosaid engine for automatically communicating lubricating fluid only tosaid engine and not to said retarder when the pressure of thelubricating fluid in said engine falls below a predetermined level forautomatically communicating lubricating fluid under pressure to thelubricating system of said engine through said retarder control valvemeans when said pressure exceeds said predetermined level wherebysufficient lubricating fluid pressure to satisfy the requirements of theengine is insured.

2. The invention ofclaim 1 wherein the priority valve means has pressuredependent means such that said valve means functions to directlubricating fluid directly to the engine when lubricating fluid pressureis low such as during engine starting.

3. The invention of claim 2 further including means for actuating thecontrol valve means such that the lubricating fluid may be directedeither through or around the retarder.

4. The invention of claim 3 wherein the priority valve means comprises apriority valve having a spool therein and spring means biasing saidspool to a first position wherein the fluid source is in fluidcommunication with the engine and out of fluid communication with thecontrol valve means.

5. The invention of claim 4 wherein means are provided for communicatingengine lubricating fluid pressure to the end of the spool opposite thespring means such that when engine operating pressure is achieved saidspool may be shifted by said pressure to a position wherein the controlvalve means is in fluid communication with the fluid source by way ofsaid priority valve means.

6. The invention of claim 5 wherein the means for communicating enginelubricating fluid pressure to the spool end is a conduit means connectedto the means adapted to connect the priority valve means to the engine.

7. The invention of claim 5 wherein the control valve means comprises acontrol valve having a spool therein and spring means biasing said spoolto a first position wherein the priority valve is in fluid communicationwith the engine by way of said control valve means and upon valveactuation the spool is shifted wherein the retarder also is brought intothe fluid circuit between the priority valve and the engine.

8. The invention of claim 7 wherein the means for actuating the controlvalve comprises a source of air pressure, an air control valve, andconduit means connecting said pressure source to said control valve byway of said air control valve.

9. The invention of claim 7 further including check valve means in thefluid circuit between the control valve and the engine to prevent returnflow of lubricant from the engine to said control valve.

10. In an internal combustion engine having a lubricant pump, lubricantfilter, a heat exchanger and a retarder, the improvement comprising aretarder control system comprising priority valve means for directinglubricant from the lubricant pump, said means being responsive tolubricant pressure whereby sufficient lubricant is directed to theengine during conditions below operating pressure in order that theengine has sufficient lubricant for proper operation at all times, and

1. In an internal combustion engine having a pressurized lubricatingsystem, a control system comprising a pressurized lubricating fluidsource and a hydrodynamic retarder operatively associated with saidengine for selective braking purposes, retarder control valve meansoperatively connected to said fluid source and said retarder forselectively activating said retarder with said lubricating fluid, andpriority valve means oPeratively connected between said fluid source andsaid retarder control valve means and further operatively connected tosaid engine for automatically communicating lubricating fluid only tosaid engine and not to said retarder when the pressure of thelubricating fluid in said engine falls below a predetermined level andfor automatically communicating lubricating fluid under pressure to thelubricating system of said engine through said retarder control valvemeans when said pressure exceeds said predetermined level wherebysufficient lubricating fluid pressure to satisfy the requirements of theengine is insured.
 2. The invention of claim 1 wherein the priorityvalve means has pressure dependent means such that said valve meansfunctions to direct lubricating fluid directly to the engine whenlubricating fluid pressure is low such as during engine starting.
 3. Theinvention of claim 2 further including means for actuating the controlvalve means such that the lubricating fluid may be directed eitherthrough or around the retarder.
 4. The invention of claim 3 wherein thepriority valve means comprises a priority valve having a spool thereinand spring means biasing said spool to a first position wherein thefluid source is in fluid communication with the engine and out of fluidcommunication with the control valve means.
 5. The invention of claim 4wherein means are provided for communicating engine lubricating fluidpressure to the end of the spool opposite the spring means such thatwhen engine operating pressure is achieved said spool may be shifted bysaid pressure to a position wherein the control valve means is in fluidcommunication with the fluid source by way of said priority valve means.6. The invention of claim 5 wherein the means for communicating enginelubricating fluid pressure to the spool end is a conduit means connectedto the means adapted to connect the priority valve means to the engine.7. The invention of claim 5 wherein the control valve means comprises acontrol valve having a spool therein and spring means biasing said spoolto a first position wherein the priority valve is in fluid communicationwith the engine by way of said control valve means and upon valveactuation the spool is shifted wherein the retarder also is brought intothe fluid circuit between the priority valve and the engine.
 8. Theinvention of claim 7 wherein the means for actuating the control valvecomprises a source of air pressure, an air control valve, and conduitmeans connecting said pressure source to said control valve by way ofsaid air control valve.
 9. The invention of claim 7 further includingcheck valve means in the fluid circuit between the control valve and theengine to prevent return flow of lubricant from the engine to saidcontrol valve.
 10. In an internal combustion engine having a lubricantpump, lubricant filter, a heat exchanger and a retarder, the improvementcomprising a retarder control system comprising priority valve means fordirecting lubricant from the lubricant pump, said means being responsiveto lubricant pressure whereby sufficient lubricant is directed to theengine during conditions below operating pressure in order that theengine has sufficient lubricant for proper operation at all times, andto control valve means after operating pressure is achieved, saidcontrol valve means functioning to direct lubricant from the valve meansthrough a heat exchanger where heat is given off, thence through thelubricant filter and into the engine during one mode of operation and,additionally, through the retarder during a second mode of operation,thus to provide selective retarder operation for braking.
 11. Theinvention as claimed in claim 10 wherein means are provided whereby theretarder is directly coupled to the engine output.